Veneer clipper

ABSTRACT

An anvil roll has a steel core and an outer portion of polyurethane. The roll is slightly rotated after a number of veneer clipping operations by a clutch which drives the roll after the roll is pushed by a knife down away from arcuate braking surfaces. An airbag normally urges the roll into engagement with the braking surfaces and is collapsed during adjustment of the roll. Operation of the clutch is prevented during the clipping operation. A double-acting cylinder drives the knife through a toggle joint linkage, and cushioning cylinder means aid in overcoming inertia of the knife at the start of a clipping cycle and also cushion the return of the knife. The cylinder has poppet check valves to rapidly admit air thereto.

This is a division of application Ser. No. 522,576 filed Nov. 11, 1974now U.S. Pat. No. 4,041,820.

Description

This invention relates to an improved veneer clipper, and has for anobject thereof the provision of an improved veneer clipper.

Another object of the invention is to provide a veneer clipper having ananvil roll provided with an elastomeric periphery.

A further object of the invention is to provide a veneer clipper havingan anvil roll having a cushioning periphery.

Another object of the invention is to provide a veneer clipper having ananvil roll which is rotated slightly after a number of clippingoperations.

Another object of the invention is to provide a veneer clipper having ananvil supported by rollers and rotated slightly.

Another object of the invention is to provide a veneer clipper having ananvil roll which is rotated by a clutch actuated by a timing means whenthere has been a predetermined number of clippings.

Another object of the invention is to provide a veneer clipper having acylinder drive with poppet valves serving as check valves.

Another object of the invention is to provide a veneer clipper in whicha drive cylinder drives a toggle drive to move a clipping knife carriageand a second cylinder drive acts on the carriage to accelerate it in itsclipping stroke and to cushion it in its retracting stroke.

Another object of the invention is to provide a veneer clipper having acylinder drive operable to reciprocate a knife carriage in a clippingstroke and a retracting stroke and booster means adapted to acceleratethe movement of the knife carriage in its reciprocation.

In the drawings:

FIG. 1 is a fragmentary front elevation view of an improved veneerclipper forming one embodiment of the invention;

FIG. 2 is an enlarged, fragmentary vertical sectional view of a portionof the improved veneer clipper of FIG. 1;

FIG. 3 is an enlarged, fragmentary vertical sectional view taken alongline 3--3 of FIG. 1;

FIG. 4 is an enlarged, fragmentary, partially sectional front elevationview of a portion of the improved veneer clipper of FIG. 1;

FIG. 5 is a schematic view of the electro-pneumatic control circuit ofthe improved veneer clipper of FIG. 1;

FIG. 6 is a schematic view of a pneumatic control circuit of theimproved veneer clipper of FIG. 1; and,

FIG. 7 is a schematic view of an electrical control circuit of theimproved veneer clipper of FIG. 1.

Referring now in detail to the drawings, there is shown therein animproved veneer clipper forming one specific embodiment of the inventionand including a knife 10 reciprocated rapidly relative to a resilientanvil roll 12 (FIG. 3) backed up by an airbag 14. The anvil roll isrotated through a small angle by an electric motor 16 (FIG. 4), anelectrically actuated clutch 18, a coupling 20 and a flexible cable 22acting as a flexible shaft. The clutch 18 may be an air actuated clutchif desired. The motor 16 is rotated continuously, and the clutch ispulsed to drive the anvil roll after the airbag 14 is collapsed topermit the anvil roll to move slightly down away from arcuate brakinglips 24 of plates 26 supporting a veneer strip 28. The lips act as abrake when the roll is pressed thereagainst.

The anvil roll 12 (FIG. 3) includes a steel core 30 and a resilientcover or sleeve 32 of elastomeric material such as, for example, 90durometer polyurethane. A pin 34 (FIG. 4) extends through a slot 36 in aferrule 38 fixed to the flexible cable 22 and slidable in a socket 40 inthe core 30. The pin 34 splines the cable 22 to the core. The anvil rollis loosely restrained laterally by L-shaped plates 42 (FIG. 3) fixed toframe member 44, angle members 46 being rigidly secured to the member 44and the plates 42. A bar 48 positioned between the plates 42 backs upthe airbag 14, and a channel member 50 is vertically slidable along theplates 42 and drops down to and rests on stops 51 when the airbag iscollapsed. The anvil roll rests on rollers 52 rotatably supported by thechannel member 50. The rollers 52 press against the cover 32 to smoothout or "heal" the periphery of the cover.

Corner angle members 60 (FIGS. 1 and 3) rigidly mounted on the member 44support top frame member 62, and carry known needle bearing guides 63vertically guiding knife supporting carriage 64. Toggle links 66 and 68pivotally secured to clevises 70, 72, 74 and 76 form toggle jointlinkages with the member 62, actuating bars 78, and the carriage 64. Thecarriage 64 has a knife support 81 to which the knife 10 is secured bybolts 82. A double-acting cylinder or primary cylinder drive 80 mountedby trunnions 86 supported by bearings 88 fixed to frame member 44 isadapted to move the actuating bars 78 in one direction for one clipping,and move the bars in the opposite direction for the succeeding clipping.The drive very rapidly moves the knife 10 down through the toggle jointlinkages to cut through the veneer 28 and to rapidly retract the knifeupwardly after such a clipping operation. The frame member 44 issupported by base 90. A continuously pressurized accelerating andcushioning cylinder drive 92 directly engages the knife carriage at alltimes except from just before the knife engages the veneer to cut theveneer to just after the knife is disengaged from the veneer. Forexample, the stroke of the knife might be about three inches, and, forone-eighth inch thick veneer, engages and clips the veneer only duringthe last one-eighth to three-sixteenths of an inch of its downwardstroke. The knife engages the veneer as it is retracted only for aboutthe first three-sixteenths of an inch of its return stroke. Piston rod94 of the accelerating and cushioning cylinder drive 92 engages thecarriage during only the first two inches of the downward stroke of thecarriage to accelerate the knife and engages the carriage during onlythe last two inches of the return of the carriage to cushion the returnof the carriage.

The double-acting cylinder 80 (FIG. 2) includes a sleeve 100, heads 102,a mounting ring 104 and spacers 106 held together by tie rods 108. Apiston 110 slidable in the sleeve 100 is positioned between valvemembers 112 having tapered ends mounted on rod 114 sealed to the pistonby O-ring 116. Piston rods 118 and 120 are slidable in bushings 122screwed into the heads 102 and are screwed onto threaded end portions124 of the rod 114. The valve members 112 are movable into and slidablealong bores 126 and 127 formed in the heads 102, and O-rings 128sealingly engage the valve members. Lines 130 and 132 are connected toports 134 and 136 leading to the bores 126 and 127. Poppet valves 138having heads 140 act as check valves and are mounted in passages in theheads 102 in communication with the ports 134 and 136. The actuatingbars 78 are pivotally connected to the piston rod 120 by a rod end 141(FIG. 2). A cover 142 covers the piston rod 118. T-shaped bleederpassages 144 and 146 in the heads 102 connect the ends of the cylinderto the passages 126 and 127, and needle valves 148 and 150 are screwedinto the passages 144 and 146.

The airbag 14 includes a resilient tube 160 sealed by hose clamps 162 toa bleeder bushing 164 (FIG. 4) and an inlet bushing (not shown) at theother end of the tube 160. The bleeder bushing has a continuously open,small bleeder passage 168 (FIGS. 3 and 4).

The piston 110 is shown in FIG. 2 about halfway through one of itsstrokes. At the start of a clipping cycle, the piston is either at oneend or the other of the cylinder sleeve 100, and the valve member 112 atthat end plugs the bore 126 or 127 and air under pressure is supplied bythe line 130 or 132 at that end. The air under pressure opens the valve138 at that end to rapidly supply the air to the adjacent end portion ofthe cylinder and rapidly drives the piston 110 to the opposite end ofthe cylinder. After the initial portion of this stroke, the valve member112 pulls out of its bore 126 or 127 and the air flows into the cylinderthrough that bore, a spring 160 of the adjacent poppet valve 138 closingthat poppet valve. Air is exhausted from the other end of the cylinderthrough the line 130 or 132 and the adjacent bore 126 or 127 until nearthe end of the stroke of the piston when the forward one of the valvemembers 112 enters the bore 126 or 127. Then a cushioning action takesplace, the air being exhausted only through the bleeder port 144 or 146,as controlled by the adjustable needle valve 148 or 150. In the nextclipping operation, the piston is driven in the opposite direction. Nuts163 screwed on rods 165 of the poppet valves 138 hold springs 167 on therods. The nuts are readily accessible for adjustment from the outside ofthe cylinder.

In FIG. 5 there is shown the pneumatic circuit of the primary cylinderdrive 80. Air under pressure is supplied from a reservoir 170 of airunder pressure to valves 172 and 174 through lines 176 and 178. Air issupplied to the reservoir 170 through air regulator 180 from an airsupply source through a line 181. Air from the line 181 is supplied bylines 182 and 184 to solenoid actuated pilot valves 186 and 188 of thevalves 172 and 174. Springs 190 bias the valves 172 and 174 toward theirexhaust conditions. For one clipping operation, a known standard scannercircuit which has a manual override actuates one of the solenoids of thevalves 186 and 188 to change the condition of that valve to connect oneend of the cylinder 100 through line 192 or 194 to air under pressure,the other valves 172 or 174 connecting the other end of the cylinder 106to exhaust. For the next clipping operation, the conditions of thevalves 172 and 174 are reversed and the piston 110 is pushed in theopposite direction. Pressure regulating valves 189 are in the lines 182and 184, and a filter 191 is in the line 181.

The cushioning cylinder drive 92 has air under pressure suppliedcontinuously to upper end of cylinder 200 thereof from a check valve 202(FIG. 6). Then, during the cushioning operation when piston 204 isdriven upwardly as the knife carriage 64 is returned to its upper orstart position, excess air is forced out of pressure relief valve 206,the valve 206 being set somewhat above line pressure of the air suppliedby the check valve 202. When a predetermined number of clipping cycleshave occurred, a counter 210 (FIG. 7), which is actuated once eachclipping cycle by a knife-actuated switch 211, closes switch 212 to atimer 214, contacts 215 of the knife switch being closed at the end ofeach clipping cycle. The timer 214 immediately closes contacts 216 and218. The closing of the contacts 216 energizes solenoid winding 220 of avalve (not shown) to collapse the airbag 14. Closing contacts 218actuates winding 222 of the clutch 18 to cause the roll 12 to be turnedthrough a few degrees, five, for example. The timer then resets to zero.A manual override switch 213 is provided.

The above-described veneer clipper very rapidly clips the continuouslymoving strip of veneer, being in the wood only 12 milliseconds or lessand using up less than 100 milliseconds for each entire clippingoperation, the veneer strip moving about 600 feet per minute. The fullclipping stroke of the knife 10 is fairly long, for example, somewhatover three inches, to permit debris to pass through the clipper, whilein only about the last three-sixteenths of an inch of the clippingstroke of the knife is the wood engaged by the knife. The rapid startgiven the knife by the cushioning cylinder drive 92 increases the speedof the knife throughout the clipping stroke. The knife-actuated switchcontacts 215 are broken whenever the knife is not retracted, which dropsout the timer 214 and to prevent adjustment of the anvil roll whenever aclipping operation is taking place.

I claim:
 1. In an improved veneer slipper,reciprocable knife means,double acting cylinder means including a cylinder having heads providedwith bores and counterbores and a piston member slidable in the cylinderand having a rod at each end slidable in the bores, the piston memberalso having shorter plug portions on the rods adapted to enter thecounterbores near the ends of the strokes of the piston member, thecylinder heads having ports connected to the counterbores, the cylindermeans also including bleeder means between the ports and end portions ofthe cylinder to control exhaust of fluid from the end portions of thecylinder after the plug portions have closed the counterbores, means forsupplying fluid under pressure selectively to the ports, actuating meansdriven by the cylinder means for reciprocating the knife means once foreach stroke of the piston member, check valve means for connecting theports to the end portions of the cylinder to bypass the bleeder meanswhen fluid under pressure is supplied to the ports, each check valvemeans being of the poppet type including a valve rod extending throughthe cylinder head, a spring on the rod exteriorly of the cylinder, andadjustable spring seat means on the rod exteriorly of the head.